BFieldComponentRadial Class Reference

The BFieldComponentRadial class. More...

#include <BFieldComponentRadial.h>

Inheritance diagram for BFieldComponentRadial:

Collaboration diagram for BFieldComponentRadial:

Classes
struct	BFieldPoint
	Magnetic field data structure. More...

Public Member Functions
	BFieldComponentRadial ()=default
	The BFieldComponentRadial constructor.
virtual	~BFieldComponentRadial ()=default
	The BFieldComponentRadial destructor.
virtual void	initialize () override
	Initializes the magnetic field component. More...
virtual ROOT::Math::XYZVector	calculate (const ROOT::Math::XYZVector &point) const override
	Calculates the magnetic field vector at the specified space point. More...
virtual void	terminate () override
	Terminates the magnetic field component. More...
void	setMapFilename (const std::string &filename)
	Sets the filename of the magnetic field map. More...
void	setMapSize (int sizeR, int sizeZ)
	Sets the size of the magnetic field map. More...
void	setMapRegionZ (double minZ, double maxZ, double offset)
	Sets the size of the magnetic field map. More...
void	setMapRegionR (double minR, double maxR)
	Sets the size of the magnetic field map. More...
void	setGridPitch (double pitchR, double pitchZ)
	Sets the grid pitch of the magnetic field map. More...
void	setKlmParameters (double srmin, double zyoke, double gaph, double iront)
	Sets parameter for EKLM. More...

Private Attributes
std::string	m_mapFilename {""}
	The filename of the magnetic field map.
std::vector< BFieldPoint >	m_mapBuffer
	The memory buffer for the magnetic field map.
int	m_mapSize [2] {0}
	The size of the map in r and z.
double	m_mapRegionZ [2] {0}
	The min and max boundaries of the map region in z.
double	m_mapOffset {0}
	Offset required because the accelerator group defines the Belle center as zero.
double	m_mapRegionR [2] {0}
	The min and max boundaries of the map region in r.
double	m_gridPitchR {0}
	The grid pitch in r.
double	m_gridPitchZ {0}
	The grid pitch in z.
double	m_igridPitchR {0}
	The reciprocal of grid pitch in r.
double	m_igridPitchZ {0}
	The reciprocal of grid pitch in z.
double	m_slotRMin {0}
	minimum radius for the gap in endyoke
double	m_endyokeZMin {0}
	minimum Z of endyoke
double	m_gapHeight {0}
	height of the gap in endyoke
double	m_ironPlateThickness {0}
	thickness of iron plate in endyoke
double	m_Layer {0}
	height of the layer (gap + iron plate) in endyoke
double	m_iLayer {0}
	reciprocal of height of the layer (gap + iron plate) in endyoke

Detailed Description

The BFieldComponentRadial class.

This class represents a radial magnetic field map. The magnetic field map is stored as a grid in cylindrical coordinates. It is defined by a minimum radius and a maximum radius, a minimum z and a maximum z value, a pitch size in both, r and z, and the number of grid points. The ZOffset is used to account for the fact that the acceleration group defines 0 to be in the center of the detector, while the detector group defines the IP to be the center. The filename points to the zip file containing the magnetic field map.

Definition at line 34 of file BFieldComponentRadial.h.

Member Function Documentation

calculate()

ROOT::Math::XYZVector calculate ( const ROOT::Math::XYZVector &  point ) const

overridevirtual

Calculates the magnetic field vector at the specified space point.

Parameters

point

The space point in Cartesian coordinates (x,y,z) in [cm] at which the magnetic field vector should be calculated.

Returns

The magnetic field vector at the given space point in [T]. Returns a zero vector XYZVector(0,0,0) if the space point lies outside the region described by the component.

Implements BFieldComponentAbs.

Definition at line 86 of file BFieldComponentRadial.cc.

{
  ROOT::Math::XYZVector B;
  // If both 'Radial' and 'Beamline' components are defined in xml file,
  // '3d' component returns zero field where 'Beamline' component is defined.
  // If no 'Beamline' component is defined in xml file, the following function will never be called.
  if (BFieldComponentBeamline::Instance().isInRange(point)) return B;
 
  //Get the z component
  double z = point.Z();
  //Check if the point lies inside the magnetic field boundaries
  if ((z < m_mapRegionZ[0]) || (z > m_mapRegionZ[1])) return B;
 
  //Get the r component
  double r2 = point.Perp2();
  //Check if the point lies inside the magnetic field boundaries
  if ((r2 < m_mapRegionR[0]*m_mapRegionR[0]) || (r2 > m_mapRegionR[1]*m_mapRegionR[1])) return B;
 
  double r = sqrt(r2);
  //Calculate the distance to the lower grid point
  double wr = (r - m_mapRegionR[0]) * m_igridPitchR;
  double wz = (z - m_mapRegionZ[0]) * m_igridPitchZ;
  //Calculate the lower index of the point in the grid
  int ir = static_cast<int>(wr);
  int iz = static_cast<int>(wz);
 
  double za = z - m_mapOffset;
  double dz_eklm = abs(za) - (m_endyokeZMin - m_gapHeight);
  if (dz_eklm > 0 && r > m_slotRMin) {
    double wl = dz_eklm * m_iLayer;
    int il = static_cast<int>(wl);
    if (il <= 16) {
      double L = m_Layer * il;
      double l = dz_eklm - L;
      int ingap = l < m_gapHeight;
      ir += ingap & (r < m_slotRMin + m_gridPitchR);
 
      double zlg = L + m_endyokeZMin, zl0 = zlg - m_gapHeight, zl1 = zlg + m_ironPlateThickness;
      if (za < 0) {
        zl0 = -zl0;
        zlg = -zlg;
        zl1 = -zl1;
      }
      double zoff = m_mapOffset - m_mapRegionZ[0];
      int izl0 = static_cast<int>((zl0 + zoff) * m_igridPitchZ);
      int izlg = static_cast<int>((zlg + zoff) * m_igridPitchZ);
      int izl1 = static_cast<int>((zl1 + zoff) * m_igridPitchZ);
      int ig = izlg == iz;
      int idz = (izl0 == iz) - (izl1 == iz) + (ingap ? -ig : ig);
      iz += (za > 0) ? idz : -idz;
    }
  }
 
  //Bring the index values within the range
  ir = min(m_mapSize[0] - 2, ir);
  iz = min(m_mapSize[1] - 2, iz);
 
  wr -= ir;
  wz -= iz;
 
  double wz0 = 1 - wz, wr0 = 1 - wr;
  //Calculate the linear approx. of the magnetic field vector
  const unsigned int strideZ = m_mapSize[1];
  const unsigned int i00 = ir * strideZ + iz, i01 = i00 + 1, i10 = i00 + strideZ, i11 = i01 + strideZ;
  const BFieldPoint* H = m_mapBuffer.data();
  double w00 = wz0 * wr0, w01 = wz * wr0, w10 = wz0 * wr, w11 = wz * wr;
  BFieldPoint Brz = H[i00] * w00 + H[i01] * w01 + H[i10] * w10 + H[i11] * w11;
 
  if (r > 0.0) {
    double norm = Brz.r / r;
    B.SetXYZ(point.X()*norm, point.Y()*norm, Brz.z);
  } else {
    B.SetZ(Brz.z);
  }
 
  return B;
}

initialize()

void initialize ( void  )

overridevirtual

Initializes the magnetic field component.

This method opens the magnetic field map file.

Reimplemented from BFieldComponentAbs.

Definition at line 25 of file BFieldComponentRadial.cc.

setGridPitch()

void setGridPitch ( double  pitchR, double  pitchZ  )

inline

Sets the grid pitch of the magnetic field map.

Parameters

pitchR	The pitch of the grid in r [cm].
pitchZ	The pitch of the grid in z [cm].

Definition at line 103 of file BFieldComponentRadial.h.

{ m_gridPitchR = pitchR; m_gridPitchZ = pitchZ; }

setKlmParameters()

void setKlmParameters ( double  srmin, double  zyoke, double  gaph, double  iront  )

inline

Sets parameter for EKLM.

Parameters

srmin	minimum radius for the gap in endyoke [cm].
zyoke	minimum Z of endyoke [cm].
gaph	height of the gap in endyoke [cm].
iront	thickness of iron plate in endyoke [cm].

Definition at line 113 of file BFieldComponentRadial.h.

setMapFilename()

void setMapFilename ( const std::string &  filename )

inline

Sets the filename of the magnetic field map.

Parameters

filename

The filename of the magnetic field map.

Definition at line 74 of file BFieldComponentRadial.h.

setMapRegionR()

void setMapRegionR ( double  minR, double  maxR  )

inline

Sets the size of the magnetic field map.

Parameters

minR	The left (min) border of the magnetic field map region in r [cm].
maxR	The right (max) border of the magnetic field map region in r [cm].

Definition at line 96 of file BFieldComponentRadial.h.

setMapRegionZ()

void setMapRegionZ ( double  minZ, double  maxZ, double  offset  )

inline

Sets the size of the magnetic field map.

Parameters

minZ	The left (min) border of the magnetic field map region in z [cm].
maxZ	The right (max) border of the magnetic field map region in z [cm].
offset	The offset in z [cm] which is required because the accelerator group defines the Belle center as zero.

Definition at line 89 of file BFieldComponentRadial.h.

setMapSize()

void setMapSize ( int  sizeR, int  sizeZ  )

inline

Sets the size of the magnetic field map.

Parameters

sizeR	The number of points in the r direction.
sizeZ	The number of points in the z direction.

Definition at line 81 of file BFieldComponentRadial.h.

terminate()

void terminate ( void  )

overridevirtual

Terminates the magnetic field component.

This method closes the magnetic field map file.

Reimplemented from BFieldComponentAbs.

Definition at line 164 of file BFieldComponentRadial.cc.

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The documentation for this class was generated from the following files:

• geometry/bfieldmap/include/BFieldComponentRadial.h
• geometry/bfieldmap/src/BFieldComponentRadial.cc